Add types to shift operations

tool/input_sdk/private/js_number.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of _interceptors;
 
 /**
  * The super interceptor class for [JSInt] and [JSDouble]. The compiler
  * recognizes this class as an interceptor, and changes references to
  * [:this:] to actually use the receiver of the method, which is
@@ skipping 375 matching lines @@
     // trick to remove one instruction in the first line.
 
     i = _shru(i, 0) - (_shru(i, 1) & 0x55555555);
     i = (i & 0x33333333) + (_shru(i, 2) & 0x33333333);
     i = 0x0F0F0F0F & (i + _shru(i, 4));
     i += _shru(i, 8);
     i += _shru(i, 16);
     return (i & 0x0000003F);
   }
 
-  static _shru(int value, int shift) => JS('int', '# >>> #', value, shift);
-  static _shrs(int value, int shift) => JS('int', '# >> #', value, shift);
-  static _ors(int a, int b) => JS('int', '# | #', a, b);
+  static int _shru(int value, int shift) => JS('int', '# >>> #', value, shift);
+  static int _shrs(int value, int shift) => JS('int', '# >> #', value, shift);
+  static int _ors(int a, int b) => JS('int', '# | #', a, b);
 
   // Assumes i is <= 32-bit
   static int _spread(int i) {
     i = _ors(i, _shrs(i, 1));
     i = _ors(i, _shrs(i, 2));
     i = _ors(i, _shrs(i, 4));
     i = _ors(i, _shrs(i, 8));
     i = _shru(_ors(i, _shrs(i, 16)), 0);
     return i;
   }
 
   Type get runtimeType => int;
 
   int operator ~() => JS('JSUInt32', r'(~#) >>> 0', this);
 }
 
 class JSDouble extends JSNumber implements double {
   const JSDouble();
   Type get runtimeType => double;
 }
 
 class JSPositiveInt extends JSInt {}
 class JSUInt32 extends JSPositiveInt {}
 class JSUInt31 extends JSUInt32 {}